Cracked Porcelain floor tile potential stress fracture

[Colshep]

I purchased porcelain floor tiles 900×900mm while setting out the tiler and noticed a slight line in the edge of a tile. Laying it on a flat surface he tapped the tile gently on the line and it cracked. The tiler believes this to be a stress fracture from the manufacturing process. Which is due to the crack having 2 different textures, going from smooth to rough. Having tap tested other tiles they believe other tiles have the same issue so does not want to lay them. The tile supplier disagrees but isn't able to provide a reason in writing for the differing textures. Has anyone else experienced this issue, or able to provide a view on why the tile has cracked in this way. Attached is a picture of the crack

Many Thanks

 

[Dave]

It was more than likely a transit fracture, did he try tiles from various boxes. ?

 

[Colshep]

Thanks Dave, would a transit fracture cause the difference textures along the break? The tiler tap tested a number of different tiles and could hear differences in frequencies across the tiles, so is not confident of the entire batch. They are to be laid over underfloor heating so we are weary of having the floor tiled and then they all crack when the heating is turned on.

 

[Dave]

Thanks Dave, would a transit fracture cause the difference textures along the break? The tiler tap tested a number of different tiles and could hear differences in frequencies across the tiles, so is not confident of the entire batch. They are to be laid over underfloor heating so we are weary of having the floor tiled and then they all crack when the heating is turned on.

The difference could be the rougher section was a break/fault in manufacturing and then the tap cleanly broke from that. Sometimes tiles can have faults from the firing process and this usually a tile here and there , not the whole batch. It’s pure guess work to be honest without fully inspecting the tiles. Check edges of the tiles and look for fault lines etc. I have never seen or heard of a full batch being faulty though .